Increase upload speed

My upload speed drops considerably when im downloading. I'm on att broadband cable (1500/256) I was wondering if there is a way to limit my download speed when i have uploads going on. Someone told me unchecking the Qos Packet scheduler under my network connections > Properties will make a difference. Does anyone know about this? I'm using xp pro.

Increase Broadband
Make sure your logged on as actually "Administrator". do not log on with any account that just has administrator privileges.
Start - run - type gpedit.msc
Expand the "local computer policy" branch
Expand the "administrative templates" branch
Expand the "network branch"
Highlight the "QoS Packet Scheduler" in left window
In right window double click the "limit reservable bandwidth" setting
On setting tab check the "enabled" item
Where it says "Bandwidth limit %" change it to read 0
Reboot if you want to but not necessary on some systems your all done. Effect is immediate on some systems. some need re-boot. I have one machine that needs to reboot first, the others didn't. Don't know why this is.